There exist many means of stabilizing elevated structures. In the petroleum industry, the earth anchor is one of the most common. Earth anchors are often used for anchoring derricks, which can often reach up to approximately one hundred feet in height. Earth anchors come in a variety of types, including: expandable wing anchors; helical (helix) anchors; flat plate anchors; and, T-bar anchors. All of these types of anchors require excavation for installation in the earth.
Typically, the derrick position is chosen in light of many factors, including: local geographical features; field equipment; and, underground structures. These same considerations as well as manufacturers' engineering specifications and governmental regulations, also mandate where derrick-supporting anchors are to be placed. Underground structures include cables, lines, conduit and piping for utilities, such as gas, electricity and water.
Frequently underground structures are compromised during excavation, which is required for placement of an earth anchor. The results can be devastating, including property damage, loss of product, environmental harm, personal injury and loss of life. Over the years, safety regulations have increased in response to injuries and death caused by excavation that compromises underground structures. Restrictions on excavation location and depth have become ever more stringent in order to avoid the above-mentioned damages.
Natural variations in local terrain, climate and geography limit placement of earth anchors. Rocks, unstable soil, previously excavated soil, and shallow ground water levels often make excavation impractical, if not impossible, in the fewer and fewer sites where excavation is allowed.
In addition to the regulatory and geographical limitation, excavation also faces constraints regarding surface and mineral interests. Rights-of-way, pits, roads, fences, and equipment limit excavation possibilities for placement of earth anchors. An example of both underground and surface limitations is a multiple well pad site. With more than one well per location, there are often separate underground utilities, property interests for both the surface and mineral estates, and multiple company ownership of structures and equipment. All the competing interests found in a multiple well pad site often impede and severely curtail excavation, thereby limiting earth anchor preparation for placement.
Vertically elevated structures require support. Earth anchors have become too cumbersome to meet the needs in the field. Thus, there is a long felt need for alternatives to earth anchors.